A seven-stage preheating system and working method for the tail of a cement kiln

Abstract

The present invention relates to the field of cement firing equipment, and particularly to a seven-stage preheating system at the tail of a cement kiln and a working method thereof. The system includes seven-stage cyclones C1-C7 arranged from top to bottom, air ducts, feed pipes, and a decomposition furnace; each cyclone has an air outlet at the top and an air inlet at the side. Among all adjacent cyclones, the air inlet of the upper-stage cyclone is connected to the air outlet of the lower-stage cyclone through an air duct; all discharge ports are connected with feed pipes; the feed pipe of any one of the cyclones C1-C5 is communicated with the air duct between the two cyclones at the rear of this cyclone; the decomposition furnace is arranged below all the cyclones; a smoke chamber communicated with the rotary kiln is further arranged below the decomposition furnace; it also includes a high-temperature fan and a raw material feed pipe. This system can reduce the waste gas temperature of the uppermost preheater to 220-240°C, greatly reduce the heat carried away by the waste gas, and thus reduce the heat consumption of the firing system.

Description

Technical Field

[0001] The present invention relates to the field of cement firing equipment, and particularly to a seven-stage preheating system and working method for the kiln tail of a cement kiln. Background Art

[0002] In the past two decades, new dry-process cement production technologies represented by the precalcining technology have been widely applied in China. So far, the cement precalcining technology is both a relatively mature and a continuously developing technology. The preheating system at the kiln tail is a key equipment that determines the heat consumption in the cement production line. In terms of the number of stages of the preheater, the domestic technology is currently mainly a five-stage preheater system. Usually, the exhaust gas temperature of the uppermost stage preheater discharged from the five-stage preheater system at the kiln tail is mostly between 310 and 350 °C. In the case of no waste heat power generation system and the use of vertical mills for raw materials with a relatively low comprehensive moisture content, a certain amount of water spraying is required for cooling to meet the requirements of drying the raw material system. In this way, not only a large amount of heat enthalpy of the kiln tail exhaust gas is not effectively utilized, but also water resources are wasted. The exhaust gas temperature of the uppermost stage preheater discharged from the six-stage preheater system at the kiln tail is mostly between 250 and 280 °C, and there is also a certain amount of energy waste.

[0003] In order to further reduce the system heat consumption and improve the technical and economic indicators, on the basis of optimizing the heat exchange effect of the preheater system, reducing the resistance loss of the preheater system, and improving the adaptability of the calciner system, and on the basis of the successful application of the five-stage preheater and six-stage preheater at the kiln tail, it is necessary to configure a seven-stage preheater system to further reduce energy consumption. Summary of the Invention

[0004] The present invention discloses a seven-stage preheating system and working method for the kiln tail of a cement kiln in view of the above technical problems existing in the prior art; this system can reduce the exhaust gas temperature of the uppermost stage preheater to 220 - 240 °C, greatly reduce the heat carried away by the exhaust gas, and thus reduce the heat consumption of the firing system.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A seven-stage preheating system for the kiln tail of a cement kiln, which system includes C1 - C7 weak vortex low-resistance cyclone cylinders, air ducts, feed pipes, and a calciner arranged from top to bottom; each cyclone cylinder is provided with an air outlet at the top, an air inlet at the side, and a feed opening at the bottom; in all adjacent cyclone cylinders, the air inlet of the upper-stage cyclone cylinder is connected to the air outlet of the lower-stage cyclone cylinder through an air duct; all discharge ports are connected with feed pipes; lock valves are provided on all feed pipes; the feed pipe of any one of C1 - C5 cyclone cylinders is communicated with the air duct between the two subsequent cyclone cylinders of this cyclone cylinder;

[0007] The calciner is provided below all the cyclones; the calciner is provided with two feed inlets corresponding to different temperature decomposition zones; the discharge pipe of the C6 cyclone is communicated with the feed inlet;

[0008] Below the calciner, there is also a smoke chamber communicated with the rotary kiln, and the discharge pipe of the C7 cyclone is communicated with the smoke chamber;

[0009] A raw material feed pipe is communicated with the C2-C1 air pipe between the C1 and C2 cyclones;

[0010] It also includes a high-temperature fan arranged on the ground; the high-temperature fan is connected with the air outlet at the top of the C1 cyclone through a pipeline.

[0011] Further, below the air lock valve of the C6 cyclone, there is a diverter valve for diverting materials to two C6 discharge pipes.

[0012] Further, according to the positions set on the preheater, the cyclones are divided into top-level cyclones and non-top-level cyclones; the top-level cyclones are arranged at the top of the preheater system, and the non-top-level cyclones are arranged below the top-level cyclones; all the cyclones include an inlet air pipe, a volute casing, an inner cylinder, a cylinder body, an upper cone and a lower cone;

[0013] The inlet air pipe is arranged at the inlet of the volute casing; the inlet air pipe is provided with an air flow inlet;

[0014] The inner cylinder is a cylindrical barrel body, and the inner cylinder and the air flow outlet are integrally welded and sleeved and welded in the volute casing;

[0015] The volute casing is a three-center equal-height variable-angle volute structure welded by three arcs with different radii; a top cover is arranged at the top of the volute casing; an air flow outlet is opened at the center of the top cover;

[0016] The cylinder body is a cylindrical hollow shell, and the upper cone and the lower cone are sequentially connected below the cylinder body; the outlet of the lower cone is a discharge port.

[0017] Further, the volute casing is composed of an R2 arc segment with O2 as the center, one end of the R2 arc segment is welded with an R1 arc segment with O1 as the center, and the other end is welded with an R3 arc segment with O3 as the center; the sum of the angles of the three arc segments with different radii is 270°, and the three arc segments are connected to the cylinder body in an equal-height variable-angle form.

[0018] Further, for non-top-level weak-vortex cyclones, the aspect ratio b / a of the air flow inlet is 0.3 to 0.6, and the ratio Fi / F of the vertical cross-sectional area Fi of the air flow inlet to the cross-sectional area F of the cylinder body is 0.2 to 0.5, and the distance between the position of the inlet air pipe close to the inner cylinder and the inner cylinder is greater than 150 mm.

[0019] Further, the eccentricity of the R2 arc section e1 / Di = 0.06 - 0.09, and the eccentricity of the R3 arc section e2 / Di = 0 - 0.4.

[0020] Further, for the top-level weak-vortex cyclone: the aspect ratio b / a of the air inlet is 0.3 - 0.6, and the ratio Fi / F of the vertical cross-sectional area Fi of the air inlet to the cross-sectional area F of the cylinder is 0.15 - 0.25. The distance between the position of the inlet duct near the inner cylinder and the inner cylinder is greater than 500 mm.

[0021] Further, the eccentricity of the R2 arc section e1 / Di = 0.1 - 0.2, and the eccentricity of the R3 arc section e2 / Di = 0.

[0022] Further, at the position where the inlet duct faces the air inlet, an inclined wall is used to guide the air flow into the volute casing; the inclined wall consists of two sections. The included angle α between the upper inclined wall and the horizontal direction is 15 - 20°, and / or the included angle β between the lower inclined wall and the horizontal direction is 60 - 70°.

[0023] Furthermore, the present invention also discloses a working method of the above-mentioned seven-stage preheating system, including the following steps:

[0024] Raw meal enters the C2 - C1 air duct through the raw meal feed pipe. The raw meal heated by the rising hot air flow enters the C1 cyclone for gas-solid separation along with the air flow. The separated raw meal enters the C3 - C2 air duct from the C1 discharge pipe, and after being heated in the same way, the raw meal enters the C2 cyclone for gas-solid separation. The separated raw meal enters the C4 - C3 air duct from the C2 discharge pipe, is heated and then enters the C3 cyclone for gas-solid separation. The separated raw meal enters the C5 - C4 air duct from the C3 discharge pipe, is heated and then enters the C4 cyclone for gas-solid separation. The separated raw meal enters the C6 - C5 air duct from the C4 discharge pipe, the heated raw meal enters the C5 cyclone for gas-solid separation. The separated raw meal enters the C7 - C6 air duct from the C5 discharge pipe, is heated and then enters the C6 cyclone for gas-solid separation. The separated raw meal is divided after leaving the C6 discharge pipe and then enters the decomposition furnace. After being decomposed in the decomposition furnace, the raw meal is carried by the hot air flow into the C7 cyclone for gas-solid separation. The separated raw meal enters the smoke chamber from the C7 discharge pipe and finally enters the rotary kiln for calcination.

[0025] The advantages and positive effects of the present invention are:

[0026] The high-efficiency and low-resistance seven-stage preheater system and working method of the present invention enhance the heat exchange efficiency between materials and gases, reduce the outlet temperature of the preheater, and reduce the heat carried away by the waste gas at the kiln tail. It will effectively reduce the waste gas temperature of the C1 cyclone to 220 - 240 °C, thereby reducing the heat consumption of the firing system. Without increasing the unit power consumption, compared with the five-stage preheater, the outlet temperature of the C1 cyclone can be reduced by 60 - 120 °C, and the unit heat consumption of the clinker can be reduced by 200 - 300 kJ / kg. Compared with the six-stage preheater, the outlet temperature of the C1 cyclone can be reduced by 30 - 60 °C, and the unit heat consumption of the clinker can be reduced by 70 - 150 kJ / kg, significantly reducing the energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the front view of the seven-stage preheating system in the preferred embodiment of the present invention;

[0028] Figure 2 is the front view of the cyclone;

[0029] Figure 3 is Figure 2 the top view of

[0030] Figure 4 is the left view of the inlet air duct of the present invention;

[0031] Figure 5 is the schematic diagram of the air flow direction in the cyclone of the present invention; where the solid line is the inlet air flow and the dashed line is the outlet air flow.

[0032] Wherein: 1, C1 cyclone; 2, C2 cyclone; 3, C3 cyclone; 4, C4 cyclone; 5, C5 cyclone; 6, C6 cyclone; 7, C7 cyclone; 8, decomposition furnace; 9, smoke chamber; 10, raw material feed pipe; 11, C2 - C1 air duct; 12, C1 discharge pipe; 13, C3 - C2 air duct; 14, C2 discharge pipe; 15, C4 - C3 air duct; 16, C3 discharge pipe; 17, C5 - C4 air duct; 18, C4 discharge pipe; 19, C6 - C5 air duct; 20, C5 discharge pipe; 21, C7 - C6 air duct; 22, C6 discharge pipe; 23, distributor valve; 24, C7 discharge pipe; 25, high-temperature fan; 26, inlet air duct; 26a, air flow inlet; 26b, outer wall; 26c, inclined wall; 27, volute casing; 27a, top cover; 27b, air flow outlet; 28, inner cylinder; 29, column; 30, upper cone; 31, lower cone; 31a, discharge opening DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to further understand the content, features and effects of the present invention, the following embodiments are exemplified and described in detail with reference to the accompanying drawings:

[0034] Such as Figure 1As shown in the figure, the present invention discloses a seven-stage preheating system for the cement kiln tail. The system includes seven-stage cyclones, air ducts, feeding pipes and a decomposition furnace 8. The seven-stage cyclones include C1 cyclone 1, C2 cyclone 2, C3 cyclone 3, C4 cyclone 4, C5 cyclone 5, C6 cyclone 6 and C7 cyclone 7 arranged from top to bottom. Each cyclone is provided with an air outlet at the top, an air inlet at the side and a feeding port at the bottom. In all adjacent cyclones, the air inlet of the upper-stage cyclone is connected to the air outlet of the lower-stage cyclone through an air duct. All discharging ports are connected with feeding pipes. A wind locking valve is arranged on the feeding pipe. The feeding pipe on any one of the five cyclones from C1 to C5 is communicated with the air duct between the two-stage cyclones behind this cyclone.

[0035] The decomposition furnace 8 is arranged below all the cyclones. The decomposition furnace 8 is provided with a feeding port. The feeding pipe of the C6 cyclone 6 is communicated with the feeding port.

[0036] A smoke chamber 9 communicated with the rotary kiln is further arranged below the decomposition furnace 8. The feeding pipe of the C7 cyclone 7 is communicated with the smoke chamber 9.

[0037] The C2-C1 air duct 11 between the C1 and C2 cyclones 2 is communicated with a raw material feeding pipe 10.

[0038] It further includes a high-temperature fan 25 arranged on the ground. The high-temperature fan 25 is connected with the air outlet at the top of the C1 cyclone 1 through a pipeline. The high-temperature fan 25 provides draft for the whole system.

[0039] During operation, the raw material enters the C2-C1 air duct 11 through the raw material feeding pipe 10. Since hot air flow drawn by the high-temperature fan 25 passes through all the air ducts, the raw material heated by the rising hot air flow enters the C1 cyclone 1 with the air flow for gas-solid separation. The separated raw material enters the C3-C2 air duct 13 from the C1 feeding pipe 12. Similarly, after being heated, the raw material enters the C2 cyclone 2 for gas-solid separation. The separated raw material enters the C4-C3 air duct 15 from the C2 feeding pipe 14. After being heated, it enters the C3 cyclone 3 for gas-solid separation. The separated raw material enters the C5-C4 air duct 17 from the C3 feeding pipe 16. After being heated, it enters the C4 cyclone 4 for gas-solid separation. The separated raw material enters the C6-C5 air duct 19 from the C4 feeding pipe 18. The heated raw material enters the C5 cyclone 5 for gas-solid separation. The separated raw material enters the C7-C6 air duct 21 from the C5 feeding pipe 20. After being heated, it enters the C6 cyclone 6 for gas-solid separation. The separated raw material is divided on the C6 feeding pipe 22 and then enters the decomposition furnace 8. After being decomposed in the decomposition furnace 8, the raw material is carried into the C7 cyclone 7 by the hot air flow for gas-solid separation. The separated raw material enters the smoke chamber 9 from the C7 feeding pipe 24 and finally enters the rotary kiln for calcination.

[0040] Since the decomposition furnace 8 is provided with two different feed inlets corresponding to decomposition zones at different temperatures, the C6 cyclone 6 is provided with two C6 discharge pipes 22 communicating with the feed inlets, and a material distribution valve 23 is provided below the air lock valve of the C6 cyclone 6 to distribute materials to the two C6 discharge pipes 22.

[0041] Specifically, all cyclones include an inlet air pipe 26, a volute casing 27, an inner cylinder 28, a cylinder body 29, an upper cone 30, and a lower cone 31; the last cyclone is provided with a flat nozzle air cannon, reducing the build-up and blockage caused by reducing atmosphere or sticky high-temperature materials.

[0042] The inlet air pipe 26 is provided at the inlet of the volute casing 27; the inlet air pipe 26 is provided with an air flow inlet 26a;

[0043] The inner cylinder 28 is a cylindrical barrel, and the inner cylinder 28 is integrally welded with the air flow outlet 27b and sleeved and welded in the volute casing 27;

[0044] The volute casing 27 is a three-center equal-height variable-angle large volute structure welded by three arcs with different radii; a top cover 27a is provided at the top of the volute casing 27; an air flow outlet 27b is opened at the center of the top cover 27a; specifically, the volute casing 27 is welded with an R2 arc section with O2 as the center at one end, welded with an R1 arc section with O1 as the center at the other end, and welded with an R3 arc section with O3 as the center at the other end; the sum of the angles of the three arc sections with different radii is 270°, and the three arc sections are connected to the lower cylinder body 29 in an equal-height variable-angle form; the connection of the three arcs with different radii is smoother, which can smoothly introduce the air flow into the cyclone, and the material reaches the cylinder wall under the action of inertia and centrifugal force, which is beneficial to improving the material separation efficiency and reducing the resistance of the cyclone; the volute spiral line adopts an equal-height variable-angle structure, and the outer side wall 26b of the connection between the volute casing 27 and the cylinder body 29 forms an angle γ with the horizontal direction; this angle γ is 50° at the air inlet and gradually increases to 90° along the volute spiral line. Thus, it can effectively prevent the occurrence of slope material accumulation and reduce the interference of material collapse on the air flow in the cyclone; the volute inlet adopts this large volute spiral structure, expanding most of the inlet area and the volute, with a larger inlet area and lower air speed, reducing the eddy current resistance in the inlet area and lower resistance loss;

[0045] The cylinder body 29 is a cylindrical hollow shell, and the upper cone and the lower cone are sequentially connected below the cylinder body 29; the outlet of the inclined cone is a discharge port 31a. The upper cone is a straight cone with a decreasing diameter from top to bottom, and the lower cone is an inclined cone with a decreasing diameter from top to bottom; the minimum angle between the axis of the inclined cone and the horizontal plane is 60°, which is convenient for the air flow to turn back while not hindering the material discharge.

[0046] Preferably, a smooth and stable inclined wall 26c is adopted at the position where the inlet air duct 26 faces the air flow inlet 26a to guide the air flow into the volute casing 27. Specifically, the inclined wall 26c is composed of two sections. The included angle α between the upper inclined wall 26c and the horizontal direction is 15-20°; the included angle β between the lower inclined wall 26c and the horizontal direction is 60-70°; this structural form in which the angle of the inclined wall 26c gradually increases from top to bottom not only plays a role in guiding the air flow, but also can ensure the stability of the air flow at the inlet of the cyclone, reduce eddy currents, and reduce resistance.

[0047] Preferably, for the C2-C7 level weak vortex cyclone: the aspect ratio b / a of the air flow inlet 26a is 0.3-0.6, and the ratio Fi / F of the vertical cross-sectional area Fi of the air flow inlet 26a to the cross-sectional area F of the column 29 is 0.2-0.5. The insertion depth s of the inner cylinder in the volute casing and the ratio s / a of the air flow inlet height a is 0.3-0.6; the distance between the inlet air duct 26 and the inner cylinder near the inner cylinder position is greater than 150 mm; it can effectively control the inlet air flow velocity and the rotational velocity of the air flow in the inner cylinder 28, reduce or avoid the collision between the inlet air flow and the return flow, and improve the separation efficiency; preferably, let the inner cylinder inner diameter be d and the effective inner diameter of the column be Di, then the ratio of the inner cylinder inner diameter d to the column inner diameter Di is d / Di = 0.4-0.6; the spiral lines of the volute casing are tangent in sequence, the eccentricity e1 / Di of the R2 arc segment is 0.06-0.09, and the eccentricity e2 / Di of the R3 arc segment is 0-0.4. When e2 = 0, the center point of the R3 arc segment coincides with the center point of the R1 arc segment and falls on the center of the column.

[0048] For the C1 level weak vortex cyclone: the aspect ratio b / a of the air flow inlet 26a is 0.3-0.6, and the ratio Fi / F of the vertical cross-sectional area Fi of the air flow inlet 26a to the cross-sectional area F of the column 29 is 0.15-0.25. The insertion depth s of the inner cylinder in the volute casing and the ratio s / a of the air flow inlet height a is 1.5-2.5; the distance between the inlet air duct 26 and the inner cylinder near the inner cylinder position is greater than 500 mm; preferably, the ratio of the inner cylinder inner diameter d to the column inner diameter Di is d / Di = 0.3-0.5. The spiral lines of the volute casing are tangent in sequence, the eccentricity e1 / Di of the R2 arc segment is 0.1-0.2, and the eccentricity e2 / Di of the R3 arc segment is 0. When e2 = 0, the center point of the R3 arc segment coincides with the center point of the R1 arc segment and falls on the center of the column. Preferably, the top-level cyclone is composed of two symmetrically arranged cyclone monomers, and the inlet air ducts of the cyclone monomers are adjacent to each other.

[0049] Experimental research and engineering practice show that the inlet air velocity v of the air flow inlet 入 has a great influence on the resistance and efficiency. Considering reducing resistance, it is hoped that v 入 is lower; considering increasing the air volume and efficiency, v 入Higher is better; single V 入 When exceeding a certain limit, the resistance surges while the efficiency increases only slightly. The optimal inlet air velocity varies depending on the structure of the cyclone preheater and the temperature of the treated gas. In the present invention, V 入 = 12 - 18 m / s; the air outlet velocity V 出 = 13 - 19 m / s. The column air velocity is 2 - 8 m / s, and the air velocity of the volute inlet air duct is 16 - 24 m / s; in the present invention, the resistance of a single cyclone can be controlled at 300 Pa. Considering the resistance balance, the separation efficiency of the non-top cyclones of the preheater reaches about 90%, and the separation efficiency of the top cyclone is controlled above 95%.

[0050] The high-efficiency and low-resistance seven-stage preheater system of the present invention enhances the heat exchange efficiency between the material and the gas, reduces the outlet temperature of the preheater, reduces the heat carried away by the kiln tail waste gas, and effectively reduces the temperature of the C1 cyclone waste gas to 220 - 240 °C, thereby reducing the heat consumption of the firing system. Without increasing the unit power consumption, the temperature at the outlet of the C1 preheater is 220 - 240 °C. Compared with the five-stage preheater, this outlet temperature can be reduced by 60 - 120 °C, and the unit heat consumption of the clinker can be reduced by 200 - 300 kJ / kg. Compared with the six-stage preheater, the outlet temperature of the C1 cyclone can be reduced by 30 - 60 °C, and the unit heat consumption of the clinker can be reduced by 70 - 150 kJ / kg. The standard coal consumption ≤ 90 kgce / t.cl, and this value is lower than that of any existing multi-stage preheater, with a significant reduction in energy consumption.

[0051] The significance of the seven-stage preheater is that since the heat exchange efficiency is increased by adding two more stages of preheaters, if not optimized, the resistance of the preheater system will also increase significantly, thereby increasing the power consumption of the high-temperature fan 25. The cyclone uses a weak-vortex and low-resistance cyclone. While maintaining a high separation efficiency, it also reduces the resistance of the cyclone. Under the same production capacity and preheater system specifications, the outlet pressure of the C1 cyclone of the seven-stage preheater can be as low as 5000 - 5500 Pa, which is only equivalent to the pressure of a general five-stage preheater system.

[0052] Generally, the increase in the number of preheater stages will lead to an increase in the height of the tower, and the civil engineering cost will increase significantly. The seven-stage preheater of the present invention will adopt a low-tower design concept to reduce the tower height and make it more economically practical.

[0053] The above has described the embodiments of the present invention in detail, but the above content is only the preferred embodiments of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A seven-stage preheating system for the cement kiln tail, characterized in that: The system includes C1-C7 weak-vortex low-resistance cyclones, air ducts, feed pipes and a decomposition furnace arranged from top to bottom; each cyclone has an air outlet at the top, an air inlet at the side, and a feed outlet at the bottom; in all adjacent cyclones, the air inlet of the upper-stage cyclone is connected to the air outlet of the lower-stage cyclone through an air duct; all discharge outlets are connected with feed pipes; a wind-lock valve is provided on each feed pipe; the feed pipe of any one of C1-C5 cyclones is communicated with the air duct between the two subsequent cyclones of this cyclone. The C1-C7 cyclones all include an inlet air duct, a volute casing, an inner cylinder, a cylinder body, an upper cone and a lower cone. The inlet air duct is arranged at the inlet of the volute casing; the inlet air duct is provided with an air flow inlet. The inner cylinder is a cylindrical barrel, and the inner cylinder and the air flow outlet are integrally welded and sleeved and welded in the volute casing. The volute casing is a three-center equal-height variable-angle volute structure welded by three arcs with different radii; a top cover is provided at the top of the volute casing; an air flow outlet is opened at the center of the top cover. The cylinder body is a cylindrical hollow casing, and the upper cone and the lower cone are successively connected below the cylinder body; the outlet of the lower cone is the feed outlet. The volute casing is composed of an R2 arc section with O2 as the center, one end of the R2 arc section is welded to an R1 arc section with O1 as the center, and the other end is welded to an R3 arc section with O3 as the center; the three arc sections are connected to the cylinder body in an equal-height variable-angle form. At the position where the inlet air duct faces the air flow inlet, a slant wall is used to guide the air flow into the volute casing; the slant wall is composed of two sections, the upper slant wall forms an angle α of 15-20° with the horizontal direction and / or, the lower slant wall forms an angle β of 60-70° with the horizontal direction. The decomposition furnace is arranged below all the cyclones; the decomposition furnace is provided with two feed inlets corresponding to different temperature decomposition areas; the feed pipe of the C6 cyclone is communicated with the feed inlet. A smoke chamber communicated with a rotary kiln is further arranged below the decomposition furnace, and the feed pipe of the C7 cyclone is communicated with the smoke chamber. The C2-C1 air duct between the C1 and C2 cyclones is communicated with a raw material feed pipe. It further includes a high-temperature blower arranged on the ground; the high-temperature blower is connected to the air outlet at the top of the C1 cyclone through a pipeline.

2. The seven-stage preheating system for the cement kiln tail according to claim 1, characterized in that: A diverter valve for diverting materials for two C6 feed pipes is provided below the wind-lock valve of the C6 cyclone.

3. The seven-stage preheating system for the cement kiln tail according to claim 1, characterized in that: For non-top-level weak-vortex cyclones, the aspect ratio b / a of the air flow inlet is 0.3-0.6; and / or, the ratio Fi / F of the vertical cross-sectional area Fi of the air flow inlet to the cross-sectional area F of the cylinder body is 0.2-0.5; and / or, the distance between the position of the inlet air duct close to the inner cylinder and the inner cylinder is greater than 150 mm.

4. The seven-stage preheating system for the cement kiln tail according to claim 1, characterized in that: The eccentricity e1 / Di of the R2 arc section is 0.06-0.09, and the eccentricity e2 / Di of the R3 arc section is 0-0.

4.

5. The seven-stage preheating system for the cement kiln tail according to claim 1, characterized in that: For the top-level weak-vortex cyclone: the aspect ratio b / a of the air flow inlet is 0.3-0.6, and the ratio Fi / F of the vertical cross-sectional area Fi of the air flow inlet to the cross-sectional area F of the cylinder body is 0.15-0.25, and the distance between the position of the inlet air duct close to the inner cylinder and the inner cylinder is greater than 500 mm.

6. The seven-stage preheating system for the cement kiln tail according to claim 5, characterized in that: The eccentricity e1 / Di of the R2 arc section is 0.1-0.2, and the eccentricity e2 / Di of the R3 arc section is 0.

7. The working method of the seven-stage preheating system for the cement kiln tail according to any one of claims 1 to 6, characterized in that The steps include the following: Raw meal enters the C2-C1 air duct through the raw meal feed pipe. The raw meal heated by the rising hot air flow enters the C1 cyclone for gas-solid separation along with the air flow. The separated raw meal enters the C3-C2 air duct from the C1 discharge pipe, and after being heated in the same way, the raw meal enters the C2 cyclone for gas-solid separation. The separated raw meal enters the C4-C3 air duct from the C2 discharge pipe, is heated and then enters the C3 cyclone for gas-solid separation. The separated raw meal enters the C5-C4 air duct from the C3 discharge pipe, is heated and then enters the C4 cyclone for gas-solid separation. The separated raw meal enters the C6-C5 air duct from the C4 discharge pipe, and the heated raw meal enters the C5 cyclone for gas-solid separation. The separated raw meal enters the C7-C6 air duct from the C5 discharge pipe, is heated and then enters the C6 cyclone for gas-solid separation. The separated raw meal is divided after coming out from the C6 discharge pipe and then enters the decomposition furnace. After being decomposed in the decomposition furnace, the raw meal is carried by the hot air flow into the C7 cyclone for gas-solid separation. The separated raw meal enters the smoke chamber from the C7 discharge pipe and finally enters the rotary kiln for calcination.

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